Si-c Polyurethane Foam Stabilizer Synthesis And D <sub> 4 </ Sub> Bulk Polymerization Kinetics

Foam stabilizer is one of the necessary materials in the foaming process of manufacturing polyurethane foams. It takes a critical role although its dosage is little.A practical and economical synthesis process has been studied in this paper. Polyhydrosiloxanes is synthesized with octamethylcyclotetrasiloxane(D4) and high hydrogen-containing polyhydrosiloxanes as materials. Then the product is manufactured by the hydrosilylation of polyhydrosiloxanes and polyethers terminated with allyl group. The thesis pay emphasis on macro-kinetics of the synthesis system, especially the synthesis system of polyhydrosiloxanes with the help of efficient analysis methods. It is established that the math model for expressing macro-kinetics of bulk polymerization of D4. It is studied that the effect of process conditions on polymerization and the structure of products. It is gotten that the methods of controlling the structure of products.Firstly, it is established that the math model for expressing macro-kinetics of bulk polymerization of D4 by the synthesis of polydimethylsiloxanes. Considering the main factors such as annular byproducts, viscosity and molecular weight regulator, it can be expressed as the following equation that the concentration of the annular products during the period of reaction:a: parameter expressing the auto-acceleration ability of reaction system b. parameter expressing the effect of molecular weight regulator on polymerization rate of D4 It is solved that the value of the parameters and the equations involving a, b and the dosage of hexamethyldisiloxane in the reaction system of bulk polymerization of D4 under the conditions that reaction temperature: 60癈 and rotation speed: 300r/min. And also it is founded that the semi-experiential equations used for controlling the average molecular weights of ultimate products.Then it is investigated that the kinetics characters and the methods of controlling the structure of products in the synthesis system of polyhydrosiloxanes. It is the result of the transfer reaction of activated centers to Si-H that cross-linking polymers come into being. And cross-linking polymers can be reduced and even be avoided by reducing the concentration of catalyst. The kinetics characters of the synthesis system are distinctly different with that of the synthesis system of polydimethylsiloxanes. the produced rate of annular byproducts is almost equivalent with the reactive rate of D4; phenomenon of auto-acceleration is disappeared and show itself auto-deceleration. It is investigated that the effect of factors such as the concentration of catalyst, reaction temperature, hydrogen-containing and the dosage of hexamethyldisiloxane on reactive rate and the structure of products, and the quantificational equations are founded. It is also founded that the methods of controlling the structure of products. It is investigated that variety of the distribution of micro-units during the period of reaction. Tendency of the balance of the distribution is reported, and the parameter 8is put forward to express the degree that the system is close to the balance of the distribution. It is found that the activated centers of the polymerization reaction of D4 are mainly produced by hydrogen-containing units and that the annular byproducts are mainly produced by the back-biting of the activated centers. It is also found that the hydrogen-containing units are easier to build bigger annulation than dimethylsiloxane units.It is found by the research of hydrosilylation that the reaction rate is mainly controlled by the rate of mass-transport between phases and that the average molecular weights of products have increased rapidly to a high level at the initial stages of reaction. Cross-linking polymers that come into being during hydrosilylation are attributed to the Si-H of Polyhydrosiloxanes and can be controlled by additive pH-adjustor: B. It is mostly appropriate while the weight of B is 0.071% to the weight of polyethers. It is found by the research of the process that it is mostly...